Roy Keane has urged Manchester United fans to not ‘be fooled’ after their dramatic FA Cup victory over Leicester.

The Red Devils booked their place in the fifth round of the competition thanks to Harry Maguire’s late header on Friday. Though replays showed the defender was well offside, VAR was not in use and the goal stood.

The result somewhat papered over the cracks of a poor United showing on the night, with Ruben Amorim’s side not having a shot on target until the 68th minute when Joshua Zirkzee made it 1-1.

United fans celebrated in the stands as they bounced back from a disappointing defeat by Crystal Palace last time out, but they are still 13th in the Premier League and struggling under Amoirm.

Keane, speaking on ITV’s coverage of the game, was critical of his side as he broke down their struggled and downplayed the result.

Roy Keane has urged fans to not ‘be fooled’ following Manchester United’s FA Cup victory

Keane questioned the apparent lack of energy in the team amid a poor first half showing

Despite winning 2-1, United did not have a shot on target until the 68th minute when they scored their first goal

‘It is a bit of everything,’ he began. ‘The manager is obviously really frustrated.

‘I don’t understand. There’s no energy – we go on about tactics, you have to play with energy, it is the starting point and enthusiasm. It doesn’t matter what system you are playing, you wont get near anyone.

‘You have to close people down. We saw two bad teams out there.

He added: ‘Don’t be fooled. You have to praise them, in the next round, but the performance itself was nowhere near good enough.’

Sir Alex Ferguson was seen in the stands alongside the likes of Sam Allardyce and Ryan Giggs, at one point caught yawning as he watched a dull first half from his former side.

But he was all smiles and cheers after Maguire headed in – a decision Keane branded ‘shocking’ – seen on his feet clapping and laughing along.

After the game, it was put to Amorim that United won the game in the famous ‘Fergie time’, but a disappointed United coach didn’t see the funny side of things when speaking to ITV.

‘We have to believe until the end, but this game has nothing to do with the time of Fergie,’ he said, straight-faced. ‘We have to do so much better with and without the ball.

Harry Maguire headed in for United in the 93rd minute, but replays showed he was well offside

United boss Ruben Amorim said it ‘was not a good day’ despite his side progressing to the fifth round of the cup

‘We had no energy in the first half, in the second it was better and we played with speed and managed to turn teams around.

‘I cannot focus on saving the season with momentum of a cup, it is not the way I see football or Man United. I am not thinking end of the season, I don’t care about that, I care about the moment and at the moment it is not good enough. Today was not a good day.’

The Portuguese’s attitude was a complete contrast from that of his predecessor, Erik ten Hag, who often used United’s FA Cup win last season as a defence when questioned on the general poor form of his side.

It was the first half that did for United, with the hosts barely laying a finger on their opponents, who are still in the Premier League relegation zone.

Rasmus Hojlund was once again largely anonymous, while Kobbie Mainoo struggled in the advanced role that Amorim now seems the favour him in.

It was at half-time when Keane pulled the biggest of his punches.

‘It has been shocking, really really poor,’ Keane began at the interval. ‘They are boring now.

‘They should remind the players in the dressing room what the game is about. There is a goal that end. No energy, there is no energy in the stadium, they are waiting for something to happen.

‘A lack of confidence, the urgency, giving it away cheaply. I just look at it from a United point of view and I’m thinking, ‘My goodness, is this what its come to?’ Nowhere near good enough.’